423 after midterm lecture notes Flashcards
1
Q
multilevel section of soil
A
- Refers to a vertical cross-section of the soil profile, revealing its distinct layers or horizons
2
Q
what is a heavy vs light texture?
A
- clay is a heavy texture
- sand is a light texture
3
Q
why do we worry about termites?
A
- they emit methane with anerobic decomposition
4
Q
nematodes
A
- microscopic worms
- ## some are big agricultural pests
5
Q
Methyl bromide
A
- used to kill nematodes and other pests
- chemically similar to chlorine in CFCs
6
Q
biological 0
A
- a term used in California that described the temperature that plant growth stops
7
Q
aeration
A
- the mechanism of improving the exchange of gases between the atmosphere and soil
- the bigger the structure, the bigger the pore size, the better aeration
8
Q
CLORPT
A
- climate, organisms, relief, parent material, time
- climate is the most important
9
Q
CL- climate
A
- Weather you get leaching or not has to do with evaporation vs precipitation
- If there is more precipitation than evaporation, then you get leaching
- Minerals stay around longer, and less translocation, in a dry climate
10
Q
O-organisms
A
- Evergreen trees, also known as conifers, keep their needles or scales all year, while deciduous trees lose their leaves annually
- Earthworms have high Calcium requirement, so they are not in acid soils
11
Q
r-relief
A
- topography
- Affects erosion, leaching
- Shape of the earth’s surface affects how soil thrives
12
Q
p-parent material
A
- usually rock, but not always
- Sandstone vs shale
- Sandstone is derived from larger sand-sized particles and shale is made of fine clay particles
- Soil texture: sand, silt, clay
- Limestone vs. serpentine
- Limestone parent material is a sedimentary rock, while serpentine parent material is a metamorphosed igneous rock
13
Q
t-time
A
- Why aren’t all soils old?
- Initially assumed it gets better and better over time
- It does tend to get deeper (except hardpans)
- BUT, in wet climates fertility declines eventually (Australia and tropical rainforests)
14
Q
Relationship between pore size, structure, and aeration
A
- Sand is larger,so the particles are larger, so the pore sizes are larger, so it is more aerated
- If it is aggregate, then you will have micropores and macropores between the aggregates
- A good aggregated clay has aeration
15
Q
aggregates
A
- Clumps of soil particles, primarily sand, silt, and clay, held together by organic matter and other binding agents
16
Q
sieves
A
- for road construction
- used by soil engineers
17
Q
ivermectin
A
- Was used to defend against covid
- An anti-parasite
- used as a horse de-wormer at first
- From estreptomicina
18
Q
largest soil animal
A
- pigs
19
Q
what we want in compost
A
- Want a good ratio of greens and browns
- Too much greens, will rot
- Brown stuff will have carbon, green stuff will have nitrogen
- need aeration because we need the oxygen so that aerobic decomposition can occur
- want high temperature
20
Q
Carbon to nitrogen ratio in humus
A
- 10 to 1
21
Q
number 1 carbon pool
A
- limestone
- then, the ocean
- then, soil
22
Q
carbon sequestation
A
- The process of capturing and storing carbon dioxide (CO2) from the atmosphere or industrial sources to mitigate climate change
23
Q
Earthworms
A
- speed up the decomposition process by breaking particles down so it is easier to weather
24
Q
black plastic
A
- one of the worst mulches
- speeds up growth because it warms it (albedo)
- effective, but uses plastic
25
Q
If you see strawberries or asparagus (spring vegetables) in the fall, they come from __
A
Southern hemisphere
26
Q
organic matter decomposition
A
- About plants
- Main constituents: cellulose, hemicellulose, lignin, and proteins
27
Q
cellulose
A
- 20-50% in plants
- in celery
- vital structural component of plant cell walls
28
Q
hemicellulose
A
- 10-30% in plants
- breaks down faster
-second only to cellulose - Found in primary and secondary cell walls
29
Q
lignin
A
- a complex organic polymer that is a major structural component of plant cell walls
- Provides rigidity and strength
- has seeds and stems
- 19-30% in plants
- 30-50% in humus
30
Q
proteins
A
- 1-15% in plants
- Proteins are broken down by microorganisms
- Releases organic matter
31
Q
inceptisols
A
- Starting to get horizons but can’t see them that well
- most likely found in mountainous regions and flood plains
- Also found in Siberia, Alaska, Canada, floodplain of Amazon, Ganges river
32
Q
sudd
A
- world’s biggest swamp
- wetland
- has inceptisols
- Central South Sudan
33
Q
aquents
A
- filled with water
- suborder of entisols
34
Q
fluvents
A
- freely drained
- floodplains with streams
- suborder of entisols
35
Q
ochrept
A
- pale
- low amount of organic matter
- suborder of entisols
36
Q
colloids
A
- where cation exchange occurs
- humus is a colloid
- Important during cation exchange
37
Q
cation exchange
A
- Cations are adsorbed, which means they stick onto the colloid
- the more negatives on the colloid, the greater amount of cation exchange we will have
38
Q
Aluminum and iron oxides
A
- give good structures to soils
39
Q
amorphous
A
- hard to describe its shape
40
Q
Silicate layered clays
A
- Form in layers of two-dimensional sheets
- microscopic atoms
- have large internal surfaces, which increases the cation exchange
- ionic double layer
41
Q
isomorphous substitution
A
- Octa: in the middle of the sheet, an aluminum gets replaced by a magnesium
- Tetra: silica gets replaced by an aluminum (+3), so there is now a negative charge
42
Q
pH
A
- equal amounts of + and - ions is a pH of 7 (neutral)
- is pH is larger, you get more - and less + (alkeline)
- if pH is smaller, you get more + and less - (acidic)
43
Q
what does pH have to do with cation exchange?
A
- the higher the pH, the greater amount of negative charges
44
Q
Attenberg limits
A
- a set of measurements that indicate the water content at which a fine-grained soil changes from one state to another
- Categories are solid, semi-solid, plastic, and liquid
- changes between these stages are called the Attenberg limits:
- shrinkage, plastic, and liquid limit
45
Q
humus
A
- at low pH, not much cation exchange
- at a decent pH, around neutral or 7, there is excellent cation exchange
46
Q
1:1
A
- Ex: kaolinite
- low cation exchange capacity
- one octa one tetra
- get OHs on one side, and Os on the other
- OH gets attracted to the O that it aligns with
- this is hydrogen bonding
47
Q
2:1
A
- ex: smectites, vermiculite
- spectites have the most shrink-swell
- higher cation exchange capacity
- two tetras one octa
- order T,O,T
48
Q
montmorillonite
A
- type of smectite
- Industrial, agricultural, and medicinal uses
49
Q
2:1:1
A
- two tetras and two octas, but there’s space between first two, one, and the last one
- order: T,O,T,O
- ex: chloride
50
Q
octahedra
A
- 8 sided, with aluminum (3+) or magnesium (2+) in center
- different ions that they can connect to
- 8 Os and OHs, but won’t add up because this one connects with another one, and so on
51
Q
Tetrahedron
A
- SiO4
- Silicon atom in the middle, and it connects to 4 atoms (usually oxygens)
- Form of a pyramid and the silicon is inside
Silicon (+4) can connect to 4 oxygens (each -2), and this is linked to another, to another, etc
52
Q
what orders are which (put on cards)
A
- smectite is vertisols
- kaolinite is ultisols
- fe, aluminum oxides are oxisols
- alfisols and mollisols are illite, vermichlite, chlorite, and even smectite
53
Q
weathering sequence
A
- start with illite, vermichlite, or chlorite
- as they weather, they go to smectite
- this goes to kaolinite
- this goes to iron and aluminum oxides
54
Q
when would aluminum ions dominate?
A
- When there is increased acidity
55
Q
what weathers out fast?
A
- calcium
- but it stays in the soil the longest
56
Q
alphalpha
A
- needs 80% of the total exchange to be calcium
57
Q
percent base saturation
A
- Refers to the percentage of the soil’s cation exchange capacity (CEC) occupied by basic cations like calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na)
58
Q
polar
A
- one side of the molecule is positive, one side is negative
- overall neutral
59
Q
capillary
A
- in narrow tubes, water will go up against gravity
- height= 0.15/radius (in cm)
- sand has big pores, so little capillary
- clay has micropores, so a lot of capillary
60
Q
hydrological cycle
A
- precipitation- water in solid or liquid form
- evaporation
- transpiration- evaporation from plants
- evapotransipration- total loss of water
- interception- water falls on trees before it gets to surface
61
Q
what happens to macro and micropores after it rains?
A
- macropores drain
- micropores hold onto the water due to the colloids
62
Q
unsaturated flow
A
- water that is in the micropores that is furthest away from colloid starts to drain
63
Q
hydrophytes
A
- wetland plants
- want a lot of water
64
Q
xerophytes
A
- drought tolerant plants
65
Q
mesophytes
A
- most of our agricultural plants are this
- Adapted to neither extremely dry nor extremely wet environments
66
Q
runoff
A
- overland flow
- water that flows over the land surface instead of infiltrating into the ground or evaporating
67
Q
infiltration
A
- Water on the ground surface enters the soil
68
Q
percolation
A
- Precipitation moves down through the soil
- eventually reaches groundwater
- due to gravity
69
Q
surface crusts
A
- if exposing soil and there is a lot of silt, that can blow into the pores and seal it closed
- do not want in agriculture
70
Q
calcifiles and calciphobes
A
- Calciphile-plant that thrives in calcium rich soil
- ex: skunk cabbage
- Calciphobe- plants that can’t thrive in calcium rich soil
- they stick on to calcium better because they don’t get too much of it
- magnolia, blueberries
71
Q
why sodium (Na) is an issue for plant growth
A
- the salt itself
- thyroid cancer
72
Q
licks
A
- areas where animal go to consume minerals from the soil
73
Q
what has the greatest adsorbtion strength?
A
- aluminum
- then, calcium
- as soil pH gets more acidic, we don’t see aluminum so calcium adsorbs more in those soils
74
Q
determinants of cation availability
A
- strength of adsorbtion
- amount of other cations
- parent material
- pH
- rate of root uptake
- aerosols (input of cations)
- fertilizers
75
Q
how to increase pH in soils
A
- lime it
- mixtures of clay and limestone
76
Q
what is needed to maintain fertile soil?
A
- erosion
- so it could be good sometimes
77
Q
iron aluminum oxides
A
- cation exchange capacity is not great
78
Q
geophagy
A
- The intentional or accidental consumption of soil
- pregnant woman do this
- for the calcium?
- to detoxify? some clays adsorb toxins
79
Q
artificial fertilizer
A
- the bacteria of decomposers are benefiting, which speeds up the decomposition, but the bacteria is becoming more prominent than the fungi, which slows down late decomposition
- tends to be applied as amonium, rather than nitrate. This lowers pH
80
Q
root uptake
A
- The process by which a plant’s roots absorb water and mineral nutrients from the soil
- water flows through the roots by osmosis
81
Q
field capacity
A
- The amount of water remaining in the soil after excess water has drained away, representing the maximum water the soil can hold against gravity
82
Q
water content-matric potential curve
A
- illustrates the relationship between soil water content and the energy status of that water
83
Q
hydrolic conductivity
A
- how rapidly water will move through pores
- moves through macropores faster than micropores
84
Q
stratification
A
- macropore between the sponges
- clay over sand, the sponge has to be saturated before the water goes into the sand
- sand over clay, water will hesitate before it drops into the clay
